In order to win more customers' business, many companies may offer discounted products or services by distributing paper-based business promotion materials, e.g., coupons. A customer, who wants to receive such discounted products or services, is required to bring a coupon with him or her to a store and return the coupon to a store clerk. By collecting coupons from the redeeming customers, a company can evaluate the effectiveness of the marketing strategy. For example, based on the number of coupons released and the number of coupons redeemed, a company may decide to adjust its marketing strategy and investment and maximize its effect. But the requirement that a customer must have a paper coupon with him or her before receiving discounted products or services is less convenient or even cumbersome. Very often, a potential customer may walk by a store without paying a visit because he or she does not have the coupon in hand.